The majority of present day integrated circuits (ICs) are implemented by using a plurality of interconnected field effect transistors (FETs). A FET includes a gate electrode as a control electrode and spaced apart source and drain regions formed in a semiconductor substrate and between which a current can flow. A control voltage applied to the gate electrode controls the flow of current through a channel between the source and drain regions. Depending upon doping during the fabrication processes a FET can be an n-channel device (NFET) or a p-channel device (PFET).
A FinFET is a type of FET that can be fabricated using very small scale processes. A FinFET is named for its use of one or more conductive fins extending between a source region and a drain region of the FinFET. A FinFET also includes a gate structure that is wrapped around the fin, with the dimensions of fin (as wrapped by gate structure) determining the effective channel of FinFET.
One of the most important semiconductor devices is the static random access memory (SRAM) cell used in many demanding memory applications. A six-transistor (6T) SRAM cell includes two PFETs for a pull-up operation, two NFETs for pull-down, and two NFETs for input/output (i.e., passgate or transfer) access. However, conventional layouts (topologies) for a 6T SRAM cell typically have jogs or notches (e.g., right angles or corners in the mask—which become patterned into the on-wafer structures) that can lead to pull-down device mismatch given the alignment challenges of sub-22 nm geometries. Also, the shared contact of the inverters is printed orthogonal to the gate necessitating lithography (printing) in two directions which can cause reduced control of critical dimensions.
Accordingly, a need exists to provide methods for fabricating an integrated circuit forming an SRAM cell that facilitates fabrication at sub-22 nm geometries. Additionally it is desirable to provide SRAM cells using FinFETs that can more fully take advantage of jogless, uni-directional SRAM processes. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.